A Cyanotic Infant: True Blue or Otherwise?

Zorc, Joseph J.; Kanic, Zlatka

doi:10.3928/0090-4481-20011001-08

Cited by 16 publications

(14 citation statements)

References 8 publications

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“…Generally, most patients tolerate their condition well even when the methaemoglobin levels rise to 40%. In cases of severe methaemoglobinaemia the treatment of choice is methylene blue singly or in combination with ascorbic acid (Wright et al , 1999; Zorc & Kanic, 2001). Although ascorbic acid reduces the methaemoglobin directly the reaction rate is slower, as highlighted in the case of the family, originally reported by Breakey and Gibson (1951), who were fed copious quantities of cabbage which caused a reduction in cyanosis over a period of several months.…”

Section: Clinical Aspects Of Rcm Types I and Iimentioning

confidence: 99%

Recessive congenital methaemoglobinaemia: cytochrome b₅ reductase deficiency

2008

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SummarySome 60 years ago, Quentin Gibson reported the first hereditary disorder involving an enzyme when he deduced that familial methaemoglobinaemia was caused by an enzymatic lesion associated with the glycolysis pathway in red blood cells. This disorder, now known as recessive congenital methaemoglobinaemia (RCM), is caused by NADH-cytochrome b5 reductase (cb 5 r) deficiency. Two distinct clinical forms, types I and II, have been recognized, both characterized by cyanosis from birth. In type II, the cyanosis is accompanied by neurological impairment and reduced life expectancy. Cytochrome b 5 reductase is composed of one FAD and one NADH binding domain linked by a hinge region. It is encoded by the CYB5R3 (previously known as DIA1) gene and more than 40 mutations have been described, some of which are common to both types of RCM. Mutations associated with type II tend to cause incorrect splicing, disruption of the active site or truncation of the protein. At present the description of the sequence variants of cb 5 r in the literature is confusing, due to the use of two conventions which differ by one codon position. Herein we propose a new system for nomenclature of cb 5 r based on recommendations of the Human Genome Variation Society. The development of a heterologous expression system has allowed the impact of naturally occurring variants of cb 5 r to be assessed and has provided insight into the function of cb 5 r.

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Section: Clinical Aspects Of Rcm Types I and Iimentioning

confidence: 99%

Recessive congenital methaemoglobinaemia: cytochrome b₅ reductase deficiency

2008

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“…In severe methaemoglobinaemia, hyperbaric oxygen and exchange transfusions are alternative therapies if the combination therapy of intravenous methylene blue and ascorbic acid fails to reduce the methaemoglobin level. 20 It should be borne in mind that methylene blue should not be used in individuals with glucose-6-phosphate dehydrogenase deficiency because it is ineffective and may cause acute haemolysis. Our patient was started with only ascorbic acid treatment because she had mild cyanosis with no other clinical symptoms.…”

Section: Resultsmentioning

confidence: 99%

Congenital methaemoglobinaemia Type I in a Turkish infant due to a novel mutation, Pro144Ser, in NADH-cytochrome b5 reductase

Percy¹,

Ören²,

Savage³

et al. 2004

Hematol J

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A baby centrally cyanosed from birth was investigated for a congenital cardiac defect. Echocardiography and angiography revealed patent foramen ovale without any other cardiac abnormality. Congenital methaemoglobinaemia was considered as the methaemoglobin level was 27%, suggesting either Hb M or a deficiency of the NADH-cytochrome b5 reductase (cytb5r) enzyme. Measurement of the cytb5r enzyme activity of this patient indicated a reduced level of 7.3 IU/g Hb (normal range 11.5-26.9 IU/g Hb). Sequencing the DIA 1 gene that encodes cytb5r revealed a novel C403T base change, predicting a proline to serine change at codon 144. This amino-acid change is not located in the enzyme's active site and does not cause loss of function. Instead it results in reduced stability of the enzyme and development of the less severe or Type I form of recessive congenital methaemoglobinaemia. The infant was started on daily ascorbic acid treatment. She has very mild cyanosis and normal growth and developmental parameters on follow-up at 10 months of age.

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“…The higher reading of pulse oximetry might be related to differences in the absorption characteristics of the methemoglobin of the two wave lengths that pulse oximetry employs. Generally, methemoglobin levels less than 20% resolve spontaneously [28].…”

Section: The Physiology Of Oxygen Transportmentioning

confidence: 99%

An approach to diagnosis and management of cyanosis and tachypnea in term infants

Sasidharan¹

2004

Pediatric Clinics of North America

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A Cyanotic Infant: True Blue or Otherwise?

Cited by 16 publications

References 8 publications

Recessive congenital methaemoglobinaemia: cytochrome b₅ reductase deficiency

Recessive congenital methaemoglobinaemia: cytochrome b₅ reductase deficiency

Congenital methaemoglobinaemia Type I in a Turkish infant due to a novel mutation, Pro144Ser, in NADH-cytochrome b5 reductase

An approach to diagnosis and management of cyanosis and tachypnea in term infants

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A Cyanotic Infant: True Blue or Otherwise?

Cited by 16 publications

References 8 publications

Recessive congenital methaemoglobinaemia: cytochrome b5 reductase deficiency

Recessive congenital methaemoglobinaemia: cytochrome b5 reductase deficiency

Congenital methaemoglobinaemia Type I in a Turkish infant due to a novel mutation, Pro144Ser, in NADH-cytochrome b5 reductase

An approach to diagnosis and management of cyanosis and tachypnea in term infants

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Recessive congenital methaemoglobinaemia: cytochrome b₅ reductase deficiency

Recessive congenital methaemoglobinaemia: cytochrome b₅ reductase deficiency